"-MIKE-" wrote in message
news
On 11/12/16 12:42 PM, dadiOH wrote:
"Gramps' shop" wrote in message
...
Need to add some lighting. T8 or T12? Probably going with 2-tube
4 footers.

More - probably - than you'll ever need/want to know (downloads a
PDF, takes a while).
http://apps1.eere.energy.gov/buildin...offer_2013.pdf

To paraphrase it, if you want to save electricity, use LED; if you
want max light, use flourescent (use electronic ballast)



My actual experience would contradict that.
Lumens are lumens.

That's true. It is also true that T-8 replacement LEDs emit fewer lumens
than do T-8 fluorescents.

However, the fluorescent lumens are coming from all areas of the round tube
while the T-8 replacement LED lumens are coming from maybe a 100 degree area
of the tube which means that the light falling on an object may be very
similar for both.

In reality, "lumens" is not a good way to measure the real life
effectiveness of illumination. For example, if one uses diffusers on their
fluorescents they are immediately losing 1/2 the light output from the
tubes.

In my shop, the fluorescent lights are recessed into a cavity between the
trusses. That cavity is painted white which reflects about 90 % of the
light hitting it which means that I am capturing some of the lost light ffom
the fluorescents that is going up/sideways (a more reflective surface could
capture more). If I were to replace them with LEDs, my shop would be less
bright.

My shop is brighter than daylight and I'm using less than 1/2 the energy
of fluorescent tubes.

How did you measure the brightness? Also, how bright and what is
"daylight"? Is it sunlight? A light cloudy sky? A dark cloudy sky?